Biochemistry Proteins with correct answers 2023-24

Biochemistry Proteins What are 7 functions of proteins? - correct answer 1) Enzymatic catalysis, 2) Mechanical Support, 3) Transport and Storage, 4) Movement, 5) Transmission of nerve impulses, 6) Regulation, 7) Protection Proteins are composed of? - correct answer alpha-L-amino acids Chiral - correct answer Has something different on all 4 bonds The alpha-carbon for all the 20 protein amino acids except glycine are chiral How do you tell if an amino acid is L or D? - correct answer L: amino is on the LEFT D: mirror image of L so amino is on the RIGHT all amino acids are L At physiological pH amino acids exist as? - correct answer zwitterions (have both + and - charge) Gly (G) - correct answer Glycine (nonpolar) Ala (A) - correct answer Alanine (nonpolar) Val (V) - correct answer Valine (nonpolar) Leu (L) - correct answer Leucine (nonpolar) Ile (I) - correct answer Isoleucine (nonpolar) Phe (F) - correct answer Phenylalanine (nonpolar) Trp (W) - correct answer Tryptophan (nonpolar) Met (M) - correct answer Methionine (nonpolar) Pro (P) - correct answer Proline (nonpolar) Ser (S) - correct answer Serine (uncharged polar) Cys (C) - correct answer Cysteine (uncharged polar) Thr (T) - correct answer Threonine (uncharged polar) Tyr (Y) - correct answer Tyrosine (uncharged polar) Asn (N) - correct answer Asparagine (uncharged polar) Gln (Q) - correct answer Gluatamine (uncharged polar) Asp (D) - correct answer Aspartate (negatively charged) Glu (E) - correct answer Glutamate (negatively charged) Lys (K) - correct answer Lysine (positively charged) Arg (R) - correct answer Arginine (positively charged) His (H) - correct answer Histidine (positively charged) You have to add what in order for a peptide bond to from between alpha-L-amino acids to make a protein - correct answer ATP (this reaction is not spontaneous, energy as ATP is required) A peptide bond has what type of character - correct answer A partial double bond character (rigid sticks and flexy strings-phi and psi bonds) Double bonds are rigid and planar. The C and N of the peptide bond do not rotate with respect to each other Naming peptide chains - correct answer This is used in naming....-yl is used when the amino acid no longer has a free carboxyl group... Ex. Phenyl-alanyl-glycyl-methionine (Phenylalanylglycylmethionine) Phosphorylation modification - correct answer (of side chains with free hydroxyl groups) -addition of phosphate group to amino acids that have already been in proteins -done to many proteins, which will change the proteins activity (increase or decrease) Glycosylation modification - correct answer (carbohydrate groups may be attached to protein via N or O linkages) - add carbs to proteins - done to many proteins because car groups is like a destination tag on the protein (it signals the cell to put those proteins into specific places) Hydroxylation modification - correct answer (of prolyl or lysyl residues) - done to just a few proteins, notably collagen which is a really important protein in connective tissue Carboxylation modification - correct answer (of glutamyl groups) - done to just a few proteins, notably in many proteins involved in blood clotting (Vitamin K) O-linked glycosylation - correct answer SER, TYR, THR, hydroxylysin (side chain made from lysine after lysine was incorporated into a protein-there is no free hydroxylysin) !! - Polysaccharide is actually built on the protein one monosaccharide at a time! N-linked glycosylation - correct answer ASN!! (always asparagine) !!! - The polysaccharide is made first and then added to the protein What can keep Lysyl Hydroxylase and Prolyl Hydroxylase in it's reduced forms during hydroxylation? - correct answer Vitamin C can keep these enzymes in their appropriate reduced states to keep them from being inappropriately oxidized Energy Investment required to disrupt particular interaction - correct answer 1) Disulfide bonds (a type of covalent bond) 100 kcal/mol 2) Ionic interactions (10 kcal/mol) 3) Hydrogen bonds (5 kcal/mol) 4) Hydrophobic interactions (3 kcal/mol) What are the most important type of interactions? - correct answer Hydrogen bonds and Hydrophobic interactions, although the weakest, are the most important in maintaining the native conformation. -They are most abundant types of interactions. Disulfide bridges are? - correct answer covalent bonds formed by the oxidation of cysteinyl residues. They may be intra-chain or inter-chain What is cystine? - correct answer it is the diamino acid fromed by the oxidation of two cysteines to produce a disulfide bond between them -NOT A DIPEPTIDE (there is no peptide bond) Why does association of nonpolar molecules occur? - correct answer Because a mixture of nonpolar compounds and water is most stable when the nonpolar molecules associate together (systems proceed to the most naturally stable state) -less H-bonds are disrupted if the nonpolar molecules are more compact therefor decreasing the energy and making it more stable Hydrophillic molecules also disrupt H-Bonds between water molecules, but the destabilization caused by the disruption of H20-H20 bonds is offset by what? - correct answer By the formation of H-Bonds between the hydrophillic molecule ad the water (solvent) What type of proteins exist in an oily solution under physiological conditions? - correct answer Membrane proteins What is the Primary Structure of a Protein? - correct answer The linear sequence (particular order) of amino acids in a protein What is the Secondary Structure of a Protein? - correct answer Regions of a protein often fit a particular stereotypic pattern 1)alpha-helices and beta-sheets What is the Tertiary Structure of a Protein? - correct answer The overall three dimensional folding of a protein. What is the Quarternary Structure of a Protein? - correct answer It's the spatial arrangement of more than one polypeptide subunit. What types of bonds maintain the Primary Structure of a Protein? - correct answer Covalent bonds (specifically peptide bonds) What types of bonds maintain the Secondary Structure of a Protein? - correct answer H-bonds What types of bonds maintain the Tertiary Structure of a Protein? - correct answer can be maintained by 3-4 types 1) H-Bonds 2) Hydrophobic interactions 3) Ionic interactions (may also have disulfide bridges) What types of bonds maintain the Quarternary Structure of a Protein? - correct answer can be maintained by 304 types 1) H-Bonds 2) Hydrophobic interactions 3) Ionic interactions (may also have disulfide bridges)